In environments that may have multiple radiation sources present, and that are potentially moderately to highly radioactive (e.g. nuclear processing or decontamination facilities), manual access is limited for safety reasons, and load limits are present with respect to mechanical and electrical support. Desirable attributes of a directional radiation detection apparatus for use in such an environment are that the apparatus should be rugged, remotely operated, self-contained, lightweight, inexpensive so that it can be disposed of after use rather than decontaminated, and it should be able to survey a radioactive environment in as little time as possible. Existing methods for detecting both the intensity and direction of one or more radiation sources in a moderately to highly radioactive environment suffer from serious drawbacks.
Two standard methods exist for measuring both the direction and intensity of a source of radiation in an environment as described above. First, a non-directional radiation detection apparatus can be transported from place to place within the environment to be surveyed. By conducting a grid search in this manner, the location of the source or sources of radiation can be determined. The major drawback of this method is that it is time intensive.
Second, a collimator can be used to create a very strongly directional detection apparatus. By pointing the collimated detector in different directions, an image of radiation intensity versus direction can be obtained. A collimator, as used in such detectors, includes a radiation shield that surrounds a radiation sensor, and an opening through which radiation from a radiation source is collimated. The major drawback of this method is that the collimator shield component must be made of a heavy material such as lead or stainless steel, such that a very strong and therefore expensive mechanism is needed to move the collimated detector so that it can be pointed in different directions. An example of this type of apparatus is disclosed in U.S. Pat. No. 7,186,963, which is incorporated herein by reference.
There remains a need for an improved directional radiation detection apparatus that is relatively lightweight and inexpensive.
This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.